Ignore event if not ready to serve as MASTER

- Issue similar to ONOS-1208 on Device Store

Change-Id: I1f3922f29d66ff68c18e364aff27ded414664889
diff --git a/core/store/dist/src/main/java/org/onosproject/store/device/impl/GossipDeviceStore.java b/core/store/dist/src/main/java/org/onosproject/store/device/impl/GossipDeviceStore.java
index 06a60d5..325242a 100644
--- a/core/store/dist/src/main/java/org/onosproject/store/device/impl/GossipDeviceStore.java
+++ b/core/store/dist/src/main/java/org/onosproject/store/device/impl/GossipDeviceStore.java
@@ -1488,6 +1488,11 @@
             ProviderId providerId = event.providerId();
             DeviceId deviceId = event.deviceId();
             DeviceDescription deviceDescription = event.deviceDescription();
+            if (!deviceClockService.isTimestampAvailable(deviceId)) {
+                // workaround for ONOS-1208
+                log.warn("Not ready to accept update. Dropping {}", deviceDescription);
+                return;
+            }
 
             try {
                 createOrUpdateDevice(providerId, deviceId, deviceDescription);
@@ -1508,6 +1513,11 @@
             ProviderId providerId = event.providerId();
             DeviceId deviceId = event.deviceId();
             List<PortDescription> portDescriptions = event.portDescriptions();
+            if (!deviceClockService.isTimestampAvailable(deviceId)) {
+                // workaround for ONOS-1208
+                log.warn("Not ready to accept update. Dropping {}", portDescriptions);
+                return;
+            }
 
             try {
                 updatePorts(providerId, deviceId, portDescriptions);